Review of ZnO Transparent Conducting Oxides for solar applications

Solar energy is a renewable clean energy and photovoltaic is one of the most effective ways to use sunlight currently. Transparent conductive films such as ITO, AZO and so on as the window layer are widely used in HIT and other high efficientcy silicon-based heterojunction solar cells. The Zinc oxide conductive thin film (ZnO) has a high transmittance at 800-1200 nm and a low resistivity, and has the potential to replace ITO film. However, it is limited by the preparation method. The resistivity of the film itself is very high, about 1E-3 Omega. cm. And the average optical transmittance in the 300-1200 nm wavelength range is less than 80%. Furnace annealing can play a key role in the elimination of stress, film of repair, recrystallization and grain growth, reducing the interface defects, improving the interface properties, and film photoelectric performance is improved. In the other hand, doping is necessary for achieve a high properties ZnO film.